PLCC footprints

[ouabache]

I am going to start working on a generate script for PLCC packages unless someone else is already working on one.

Do we have a wish list of items that we need someone to create?

[dbrgn]

Hm, maybe that could be integrated into the QFP generator? https://github.com/LibrePCB/librepcb-parts-generator/blob/master/generate_qfp.py

From Wikipedia:

A package related to QFP is PLCC which is similar but has pins with larger pitch, 1.27 mm (or 1/20 inch), curved up underneath a thicker body to simplify socketing (soldering is also possible).

Is there a document (e.g. from JEDEC) that standardizes PLCC footprints?

[ouabache]

That was my approach was to take that script and modify it to produce the plcc packages. The main thing is getting the IPC names right.

We may also need another pkgcat for plcc's

Right now I am fighting with jedec to try and get the right docs

On Sat, Jan 25, 2020 at 11:57 AM Danilo Bargen notifications@github.com wrote:

Hm, maybe that could be integrated into the QFP generator? https://github.com/LibrePCB/librepcb-parts-generator/blob/master/generate_qfp.py

From Wikipedia:

A package related to QFP is PLCC which is similar but has pins with larger pitch, 1.27 mm (or 1/20 inch), curved up underneath a thicker body to simplify socketing (soldering is also possible).

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[dbrgn]

IPC name is as follows:

PLCC + Pin Qty. + P Pitch _ Lead Span L1 X Lead Span L2 Nominal X Height + L Lead Width

[dbrgn]

Oh, what might make this a bit more difficult: PLCC packages have different pin numbering scheme. Pin 1 is at the middle of a side, not at a corner.

[dbrgn]

I think after about 15 minutes of searching I found the relevant standard: MO-047: https://www.jedec.org/system/files/docs/Mo-047b.pdf (free registration required).

Topline PLCC packages may also be helpful: https://www.topline.tv/PLCC.html

[ouabache]

This seems to work:

    for p in range(1, config.lead_count + 1):
            group_size = config.lead_count // 4
            mid = (group_size + 1) // 2
            x = (p + mid )
            if x > config.lead_count : x = x - config.lead_count
            pad_uuid = uuid_pads[x - 1]

On Sat, Jan 25, 2020 at 1:34 PM Danilo Bargen notifications@github.com wrote:

Oh, what might make this a bit more difficult: PLCC packages have different pin numbering scheme. Pin 1 is at the middle of a side, not at a corner.

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[ouabache]

I found another ipc-7351B that calls out Plastic Leaded Chip Carriers .................................................. PLCC + Pitch P + Lead Span L1 X Lead Span L2 Nominal X Height - Pin Qty

On Sat, Jan 25, 2020 at 1:32 PM Danilo Bargen notifications@github.com wrote:

IPC name is as follows:

PLCC + Pin Qty. + P Pitch _ Lead Span L1 X Lead Span L2 Nominal X Height + L Lead Width

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[dbrgn]

I found another ipc-7351B that calls out

Use IPC7351-C, not -B: https://www.pcblibraries.com/downloads/Guidelines!Library-Expert-Land-Pattern-Naming-Convention.asp

[ouabache]

Changes made. Pull request is in

On Sun, Jan 26, 2020 at 3:48 AM Danilo Bargen notifications@github.com wrote:

I found another ipc-7351B that calls out

Use IPC7351-C, not -B: https://www.pcblibraries.com/downloads/Guidelines!Library-Expert-Land-Pattern-Naming-Convention.asp

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